Sirius: Alco "Firefly" version

[RReid]

That's a nice trick for aging the brass. One to remember.

[redhouseluv]

I'm trying the soldering and ending up with the flux turning crusty white rather the turning to a clear liquid which I've seen in videos. I tried diluting the flux some more but just ended up with a similar result.

I wondered if I need more heat and the crust will turn liquid, but was worried I'd melt the nipple?

[Jasonb]

You want the flux a lot thicker, more like tooth paste.

As you start to heat the water will boil off and leave a crusty deposit, it then starts to soften and look like boiling sugar and then will finally turn to a liquid and that is when you feed in the rod.

<a href="https://www.youtube.com/watch?v=Rz4ScC294zg" target="_blank">http://www.youtube.com/watch?v=Rz4ScC294zg</a>

And one I did a while ago for somebody else

<a href="https://www.youtube.com/watch?v=EnTs7jx4Zc0" target="_blank">http://www.youtube.com/watch?v=EnTs7jx4Zc0</a>

[redhouseluv]

Still having problems - flux is turning black this time, haven't got the solder to melt yet

https://www.youtube.com/shorts/p5u-jR8OlS0

[redhouseluv]

This time the flux started to run clear and the nipple was glowing, but still no real solder melting visible ...... but the nipple is fixed, but its not right.....

Running out of tenacity

[uuu]

By clamping the tube in the vice you're conducting the heat away to a nice bug lump of steel.  if you could support the pipe using a firebrick or even just resting on the fireproof surface, you might get a better result.  The pipe is always going to absorb more heat than the nipple, so you can direct the flame onto it for more time than the nipple.

In the (excellent) videos, you can see how much heat is being used for quite small parts.  In the first one, the metal is very thin, but still needs a good blast.  And you'll see that even after there's a molten blob of solder on part of the joint, it needs more heat to get it to flash right in.

You could try the other flux.  Make sure you have flux in the joint - it should flow in by capillary action, but putting some in will help.

Keep at it.  These skills come with practice - after a while you'll wonder what all the fuss was about.

Wilf

[AVTUR]

Wilf's advice on support of work is good. Too much heat just "burns" the flux. Instead of waving a rod of solder about try placing a small piece of solder with the flux at the joint. It may be blown about by the flame but when it melts and wets the surface of the metal start adding more solder. The problem is that the cold rod of solder conducts heat away from the metal so chilling the surface to below the solder's point. This becomes a problem with steel, particularly stainless which is a poor conductor of heat.

I believe you cannot have too much flux.

[redhouseluv]

I will persevere with this over the weekend, it'll be one of those things where hopefully it clicks when the combo of heat, flux and solder is just right

[crueby]

Which specific solder brand/grade are you using? The silver solders come in a range of grades from 'extra easy', 'easy', 'medium', 'hard'. The easy ones melt at a lower temperature than the hard end of the line. For most things I prefer the 'easy' grade, it melts and flows very nicely. The hard versions take a much higher temperature, and on soft metals like copper/brass you are closer to melting the metal.

It looks like you have one of the other alloys than the normal silver solder - one that is bronze color? If so, you need to know what the melting point of it is compared to the silver ones, it may be too high a melting point for what you are trying to do.

I buy the version that is wire, around .020" diameter (it comes in different diameters too, that is personal preference), made for the jewelry market. Different people like doing it different ways, I like putting a short piece of wire on the joint and heating from the other side of the metal till it melts the solder. The wire version lets me bend it to fit around things like a pipe, though as others mentioned on small pipes like yours it can fall off, so those cases I'll use the long wire and touch it to the joint when it gets hot (flux has melted and gone clear).

[Jasonb]

Here easy, medium and hard are the terms used for jewelry solders which have more silver in them and are more  expensive than needed for model engineering work. and require more heat

The typical lowest melting point silver solder used here is a 55% CAD free solder that melts at 630-660 degC and that is what should be used for this and most other jobs. This has a lower melting point than "Easy" solder which is around 700degC and 65% silver content. Nearest to our 55% in the US would be Harris Safety-silv 56

One trick if you have say 1.5mm rods is to take a clean faced hammer and beat the strip to make it flat, you can then feed in the flat end which won't wick away the heat or if you want a really small amount use tin snips to cut the flat end into 3 strips of equal width.

To me that last photo looks like solder has run, pickle it and see what is under the old flux.

[redhouseluv]

This is the last solder I bought, not sure if its right for the job or not, but seems to have a higher melting point than has been indicated.

Johnson Matthey Silverflo 24 High Temperature Solder
24% Silver Solder - 1.5mm diameter x 300mm long Silverflo 24 Rod x1
Temperature melting range 740 - 800°C

I'll try the thin strips method and try on the firebrick rather than the vice, what's the best thing for 'pickling'?

[Jasonb]

beating that thin will still need a lot of heat and you will be getting close to melting the brass, save it for a steel fabrication or a job were you want to solder in stages without the previous one melting.

What is the one coiled in the small zip top bag.

I use "brick cleaner" from the local builders Merchant which is quite aggressive. Citric acid is safer if a bit slower.

https://cupalloys.co.uk/category/brazing-ancillaries/

[uuu]

Wow -aha.

That's a very high temperature solder - much hotter than the 55% silver solder that most of us use as a standard.  I must admit I've never tried one that goes that high.  I use 42% as my highest rated stuff.   

Cupalloys (a supplier recommended earlier) notes about the 24%:  Its high melting point often requires the use of oxy-acetylene heating

If you can get some 55% you ought to find things much easier.

Wilf

[redhouseluv]

Right, now we're getting to the bottom of this mystery and my misery 

Let me find some 55% silver solder and see where that gets me

[redhouseluv]

What is the one coiled in the small zip top bag.

https://cupalloys.co.uk/category/brazing-ancillaries/

Going through my past purchases I think the zip lock bag contains is this as its very long compared to the short rods and more like what is required?

0.5mm silver solder wire 55% silver 6 ft long melting range 630-660 oc

Seems extraordinarily cheap as its was £6.90 from Macc Models, the 455 Silver Solder 0.7mm dia x 500mm (5 Rod Pack) from cupalloys is £17.86?